The Division of Acquired Immune Deficiency Syndrome, and the Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, are actively engaged in programs to discover and develop therapeutics for the treatment of HIV infection and AIDS- associated opportunistic infections. Therapeutics development involves a number of steps at both the preclinical and clinical level. Preclinical development may involve chemical analyses, analytical methods development, efficacy and toxicity evaluations, drug stability studies, and development of the pharmaceutical dosage form. This contract will provide analytical and pharmaceutical chemistry support needed to verify the identity and assess the purity of bulk drugs and pharmaceutical dosage forms; perform necessary preformulation studies including determination of physiochemical properties (pH-rate and pH- solubility profiles, pK-a-s, stability, etc.); develop and validate stability indicating assays and assays to quantitate drug and metabolite concentrations in biologic fluids; and assess the stability and quality of the final dosage form. This information may be required prior to: in vitro or in vivo efficacy studies, pharmacokinetic and toxicology studies, pharmaceutical dosage form manufacture, or the initiation of clinical trials. This effort will assure that materials of high purity and reproducibility are used in these studies and will conform to Good Laboratory Practice regulations when required.